Funny that the ads for the Nordic Track is opposite the Skier's Edge. I could barely give away two Nordic Tracks last year (the 'buyer' came 3 hours, one way, and brought a couple bottles of wine which were unexpected) yet the Skier's Edge is in it's umpteenth revision.
My buddy was a Skier's Edge sponsored racer for a couple years and competed in the Masters International races, both here and in Europe. He placed well despite the first races he went to in Europe were raced on borrowed equipement when his gear didn't make it where he was. It is a pretty nice, albeit expensive, training system. He has developed various exercises on it that utilize the sliding platform, but not the traditional skiing actions. For one he gets on his knees and slides the foot stand away then towards himself, kind of like with that rolling wheel that you see in the infomercials. He figures, get more exercises out of an expensive piece of hardware.